Pyroxylin compound



UNITED STATES.

PATENT OFFICE.

JOHN H. STEVENS, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE OELLULOID COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

PYROXYLIN COMPOUND.

SPECIFICATION forming part of Letters Patent No. 613,400, dated November 1, 1898.

Application filed March 25, 1898. Serial No. 675,071. (No specimens.)

To all whom it may concern:

Be it known that I, JOHN H. STEVENS, of the city of Newark, county of Essex, and State of New Jersey, have in vented certain new and useful Improvements in Pyroxylin Com pounds, of which improvements the following is a specification.

Pyroxylin or nitrated cellulose is liable t spontaneous decomposition, especially when impure or imperfectly freed from the acid remaining after the treatment of cotton or paper or other celiulose fiber in the nitratingbath. This has led inventors to adopt. the use of antacid or preserving substances in pyroxylin mixtures. The oflice of the preserver is to take up the free acid developed by the decomposing pyroxylin and by its presence prevent or minimize the tendency to further decomposition.

The discovery of the successful antacids used by the art has involved considerable study and experiment, because many substances which might be supposed to work are found to be deficient or useless. Some sub stances which are well-known neutralizers of acids are incompatible with pyroxylin and its solutions and really hasten decomposition instead of preventing or retarding it.

So many different effects are required because of the many different uses and applications of these compounds that the operator needs a large range of antacids from which to select the one best suited to his purpose. Hence any increase in the number of useful preserving substances is a welcome aid to the operator.

It is the object of the present invention to furnish the art with a new class of substances to be used in connection with pyroxylin or its compounds to prevent or retard acid decomposition. This new group consists of the salts of succinic acid. This acid and its salts are so well known to chemists as to require no special description either as to their chemical and physical characteristics or their modes of manufacture.

By the salts of succinic acid I mean the combination of succinic acid with an inorganic base. I am aware that esters of Suecinic acid were regarded as salts by the older chemists and are so spoken of in the older works on chemistry; but I exclude these esters from my invention, as they are not at all available for my purpose.

Among the various salts of succinic acid available I prefer to use potassium succinate, especially because of its solubility in or compatibility with the usual solvents of pyroxylin, such as alcohol and wood-spirit.

In practice I proceed as follows: In treating, pyroxylin which is to be used or sold in a dry state unmixed with solvents I moisten the pyroxylin with a solution of potassium succinate. This solution can be aqueous or otherwise so long as it does not have a substantial solvent effect on the pyroxylin. On drying the pyroxylin the potassium succinate is leftin close contact with every part of the pyroxylin and preserves it against acid decomposition. Fibrous pyroxylin, however, as is well known, will not stand the effects of heat and time as well as if the pyroxylin is protected by means of solvents. Potassium succinate therefore does not lessen the danger from fire or explosion in transporting or storing dry pyroxylin. The antacid salt simply has the effect of preventing or delaying for a long time the usual acid decomposition, which makes the pyroxylin dangerous to keep in a dry state, especially in masses, where through lack of surface exposure the heat caused by decomposition is apt to accumulate and produce serious results.

In treating pyroxylin compounds made with solvents I preferably dissolve the potassium succinate in wood-spirit or grain-alcohol and use this solution as part of the liquid solvent, although I can add it to dissolved masses in a finely-powdered condition and rely on the masticating operation to eifect a thorough incorporation. It is best, however, to use solutions of the potassium succinate whenever possible, for solutions penetrate better, and thus bring every particle of the pyroxylin into contact with the preserving substance. In compounds made by dissolving pyroxylin in acetone-smokeless powder, for instance I recommend the use of a wood-spirit solution of the preserving-salt.

Potassium succinate is useful in forming the thin transparent sheets which are so much used for decorative purposes. By using it too in a proportion of one per cent, by weight, to the amount of pyroxylin it gives pale effects superior to the well known antacid agent urea. It is also, proportion for proportion, superior to urea in preventing decomposition. In using more than one per cent. of potassium succinate there is a tendency to opacity of the solutions and to render solid products somewhat adhesive under heat and pressure. I would not recommend or advise the use of more than two per cent. for these reasons. An increase in proportion is also accompanied by an increased tendency to discoloration or yellowness.

I have also successfully used the sodium succinate; but because of its feeble power this salt acts best in two-per-cent. proportion. To get the best transparency with sodium succinate, the salt should be used in solution and the solution filtered free from insoluble specks.

Ammonium succinate also gives good results. For high transparency and paleness one per cent. is about the right proportion. Two per cent. gives extraordinary stability, with a slight tendency to yellowness, which, however, fits it specially for use in tortoiseshell and yellow-amber imitations.

As to the general use of the salts of' succinic acid I would recommend, first of all, the potassium succinate and confine the others mainly to those pyroxylin products which are required to be protected by an antacid substance, but at the same time do not specially call for transparent effects. As a rule the salts of succinic acid are feeble in their preservin g eflect in proportion to their insolubility. Hence for the salts of succinic acid other than the succinates of sodium, lithium, potassium, and ammonium, which I find are fairly soluble in the usual alcoholic ingredients, I would recommend the use of from two to four per cent. and in finely-powdered condition.

Pyroxylin compounds, as is well known, embrace pyroxylin itself and its solutions whether liquid, pasty, or solid. They are used for varnishes, lacquers, waterproofing solutions, and in stiff or hard masses for rolling, stufiing, molding, and carving.

Explosive compounds are used in gunnery and blasting in the shape of fibrous guneotton and smokeless or other powders.

Among the succinate salts which I have used with success are those of calcium and magnesium. The calcium and magnesium salts are weaker in preserving power than potassium succinate. They are also less soluble in alcohol.

I have no explanation to offer for the antacid power residing in bases already saturated with an acid. I find, however, that this power depends to a considerable extent upon the nature of the acid radical in the salt and that the presence of this acid radical, even when used in combination with other acid radicals to form salts, gives antacid power at least proportionate to its presence in the salt. To illustrate the effect or the nature of the acid radical, I can say that while potassium succinate possesses preserving power in pyroxylin compounds potassium phosphate has little or no antacid effect. Hence I include in my invention the salts of succinic acid in pyroxylin compounds whether the salts are simple, compound, mixed, or combined chemically with other substances.

Having fully instructed the operator in my invention, what I claim, and desire to secure by Letters Patent, is

1. A new composition of matter consisting of pyroxylin and a salt of succinic acid, said salt having an inorganic base, substantially as described.

2. A new composition of matter consisting of pyroxylin, a solvent of the same, and a salt of suocinic acid, said salt having an inorganic base, substantially as described.

3. A new composition of matter containing pyroxylin and potassium succinate.

JOHN II. STEVENS.

lVitnesses:

ABRAHAM MANNERS, ABRAM V. DUNCAN. 

